Internal combustion engines with at least two rows of cylinders with overhead camshafts

ABSTRACT

A V-form internal combustion engine includes two rows of cylinders with overhead camshafts driven by an intermediate shaft arranged between the two rows of cylinders parallel to the latter and itself rotated by the crankshaft of the engine through a generally reducing transmission device. The two transmission devices include two drive gears keyed on the intermediate shaft at positions selected so that the corresponding driven gears borne by the camshafts are situated between two cams relating to two successive cylinders of the corresponding row of cylinders, whereby reduction in the length of the camshafts and in the engine cylinder heads is effected.

United States Patent Alfieri 1 1 July 4,1972

[54] INTERNAL COMBUSTION ENGINES WITH AT LEAST TWO ROWS OF CYLINDERSWITH OVERHEAD CAMSHAFTS [72) Inventor: Giulio Altieri, Modena, Italy[73] Assignee'. Officine Alfieri Maserati, Modena, Italy [22] Filed:Aug. 20, 1970 [21] Appl No: 65,431

[58] Field of Search 123/9027, 90.31, 55 V, 195 A, 123/198, 52 R, 52 MV,DIG. 1, DIG, 6, DIG. 7

[56] References Cited UNlTED STATES PATENTS 1,173,105 2/1916 Fekete123/195 A X 1,312,555 8/1919 McCain 123/55 V 1,424,428 8/1922 Vincent123/9027 X FOREIGN PATENTS OR APPLICATIONS 421,359 9/1933 Great Britain.,123/90.3l

Primary ExaminerAl Lawrence Smith AtlomeyLarson, Taylor and Hinds [57]ABSTRACT A Vform internal combustion engine includes two rows ofcylinders with overhead camshafts driven by an intermediate shaftarranged between the two rows of cylinders parallel to the latter anditself rotated by the crankshaft of the engine through a generallyreducing transmission device, The two transmission devices include twodrive gears keyed on the in terrnediate shaft at positions selected sothat the corresponding driven gears borne by the camshafts are situatedbetween two cams relating to two successive cylinders of thecorresponding row of cylinders, whereby reduction in the length of theCamshafts and in the engine cylinder heads is effected 3 Claims, 4Drawing Figures INTERNAL COMBUSTION ENGINES WITH AT LEAST TWO ROWS OFCYLINDERS WITH OVERHEAD CAMSHAFIS The invention relates to internalcombustion engines including at least two similar rows of severalcylinders in each of which the valves of the cylinders are actuated byat least one overhead camshaft; and it relates more particularly,because it is in this case that its application seems to have the mostinterest, but not exclusively, among these engines, to those of the Vform type, especially for automobile vehicles.

It is a particular object of the invention to render engines of the typeconcerned such that they respond to the various desiderata of practicebetter than hitherto and especially so that they effect a reduction inbulk of the actuating mechanism for the camshafts and for certainaccessories of the engine, and, preferably, so that it is possible, inaddition, to use identical cylinder heads for the two rows of cylinders.

The internal combustion engine according to the invention comprises atleast two similar rows of several cylinders in each of which the valvesof the cylinders are actuated by at least one overhead camshaft, thecamshaft of the two rows of cylinders being rotated, by means of twochain or notched belt and pinion transmission devices, by anintermediate shaft arranged between the said rows of cylinders parallelto the latter and itself rotated by the crankshaft of the engine througha generally reducing transmission device, the said engine beingcharacterized by the fact that the two said transmission devicescomprise respectively two drive gears keyed on the said intermediateshaft at emplacements selected so that the corresponding driven gearsborne by the carnshafts are situated between two cams relating to twosuccessive cylinders of the corresponding row of cylinders, thisarrangement enabling reduction in the length of the camshafts and in theengine's cylinder heads.

Preferably, the driven gears of the two corresponding camshafts, belongrespectively to two similar rows of several cylinders, occupysymmetrical positions with respect to the axis enabling the cylinderheads of the two rows of cylinders to be made to coincide theoreticallyby a rotation of 180 around their axis, whereby it is possible to adoptidentical cylinder heads for the two said rows of cylinders, whichobviously constitutes an economy in the cost of manufacture of theengine.

It will then, advantageously, be possible to arrange the intermediateshaft in the longitudinal plane of symmetry of the engine, so the twotransmission devices relating respectively to the two camshafts of thetwo rows of cylinders are themselves identical, which enables an economyto be effected.

In addition, it is advantageous to use the said intermediate shaft fordriving, directly or indirectly, accessories borne by the engine or bythe structure equipped with this engine (body in the case of an enginefor an automobile vehicle), the accessory transmission system, in thelatter case, being advantageously capable of being a flexibletransmission system protecting the said accessory from the vibrations ofthe engine.

If necessary or useful, the intermediate shaft could be made to includean extension intended to receive an accessory or a drive for theactuation of such an accessory.

Finally, with the object of licening, the intermediate shaft couldadvantageously be provided as tubular.

The invention relates more particularly, and this by way of newindustrial products, to engines of the type concerned including theapplication of the previously explained features, as well as the specialelements and tools adapted for their manufacture and the assemblies orinstallations, fixed or movable, especially automobile vehicles,equipped with similar engines.

In order that the invention may be more fully understood, a referredembodiment of an internal combustion engine according to the inventionwould be described below, purely by way of illustrative but non limitingexample, with reference to the accompanying drawings, in which:

FIGS. 1 and 2, show, in diagrammatic manner, respectively in end view inthe direction of the arrow I FIG. 2 and in plan of view, an embodimentof a V form engine constructed according to the invention; and

FIGS. 3 and 4, are diagrammatical cross-sections effected respectivelyalong the lines III-III and IVIV of FIG. 2.

The engine shown in end view in FIG. 1 and in plan view in FIG. 2 is aninternal combustion engine with two rows of several cylinders Ia and lb(for example four cylinders per row) arranged symmetrically with respectto the longitudinal plane P passing through the axis of the crankshaft 2of the engrne.

The cylinders of one of the rows (identified in FIG. 2 by theirrespective plugs 3) are preferably slightly displaced longitudinallywith respect to the cylinders of the other row, the two rows ofcylinders having however a symmetry with respect to an axis XX situatedin the plan P oriented perpendicularly to the axis of the crankshaft,which symmetry enables theoretically the row of cylinders Ia to be madecoincide with the row of cylinders lb by rotation of the said rowcylinders In by l around this axis XX.

Each row of the cylinders is equipped, for control of its valves, withat least one camshaft and, preferably, with two camshafis 40 for the rowof cylinders 10 and 4b for the row of cylinders lb, two cams relating tothe successive cylinders being denoted by the reference 4 on each of therespective camshaft.

There is then provided, to rotate the pairs of camshafts 4a and 4b, twochain (or notched belt) and pinion 6a and 6b transmission devices whichwill be more explicitly considered below and which are moved by anintermediate shaft 7 extending longitudinally between the rows ofcylinders Ia and lb with, preferably, its axis situated in the plane ofsymmetry P, the abovesaid intermediate shaft 7 being itself driven bycrankshaft of the engine by a reducing device, for example a chain 8 andpinion 9 and 10 reducer as clearly shown in FIG.

This being the case and according to the main feature of the invention,the transmission devices 60 and 6b intended for the actuation of thepairs of camshafts 4a and 4b are ranged in emplacements such that, alongthe intermediate shaft 7, the driven gears (11a for the transmissiondevice 6a and llb for the transmission device 6b) keyed on the camshaftsare situated between the cams 5 relating to two successive cylinders ofthe row of the cylinders concerned as clearly visible in FIG. 2.

Preferably, it is arranged that the driven gears Ila, relating to one ofthe rows of cylinders Ia, have a symmetry, with respect to the axis ofsymmetry XX of the two rows of cylin ders, with the corresponding drivengears llb relating to the other row of cylinders, which enables then theprovision of identical cylinder heads for the two rows of cylinders andof the two cylinder covers 12a and 12b (shown in mixed line in FIG. 2),also identical.

These cylinder head covers Ila and 12b can then be of H form with thetransverse bar of the H displaced, the said bar being situated at thelevel of the corresponding transmission device 6a or 6b.

Each transmission system 6a and 6b can then include, as shown in FIG. 3for the system 6a and FIG. 4 for the system 6b, a chain (13a or 13b)passing over the corresponding driven pinions (Ila or 11b), over a drivegear (14a or 14b) keyed on the intermediate shaft 7 and on a tensioneror 15b.

The intermediate shah 7 includes, on the opposite side to its drive gear10, an extension 70 projecting beyond the rows of cylinders and on whichis keyed the rotor of a rotary accessory such, for example, as a waterpump 16.

The abovesaid shaft can also bear, in its part between two rows ofcylinders, other rotary elements to actuate, for example a gear 17 fordriving an ignition device and a drive means 18 for an externalaccessory.

There can then, advantageously, to lower the cost price of the engine,be constituted as the intennr. diate shaft 7 a single part in which aredirectly machined the various gears and drive means which have to beborne by the said shaft.

Finally, with the object of lightening, intermediate shaft 7 can beprovided as tubular.

As a result of which, there is provided an internal combustion engine ofwhich the advantages (compactness and simplicity of drives of thecamshafts and of the accessories, identical cylinder heads, especially)result sufficiently clearly from the preceding description, so that itis unnecessary to enter, on the subject, into further complementaryexplanation.

As is selfevident, and as emerges already besides from the precedingdescription, the invention is in no way limited to that of its methodsof application, nor to those of its methods of production of its variousparts, which have been more particularly envisaged, it embraces, on thecontrary, all variations.

1 claim:

1. In an internal combustion engine comprising at least two similar rowsof several cylinders, an interchangeable overhead camshaft drivearrangement, wherein the camshafts of the two rows of cylinders arerotated, through two chain or notched belt transmission devices andgears, through an intennediate shaft arranged between said rows ofcylinders parallel to the latter and itself rotated by the crankshaft ofthe engine through a generally reducing transmission device, the twosaid transmission devices including respectively two drive gears keyedon the said intermediate shaft at positions selected so that thecorresponding driven gears borne by the camshafts are situated betweentwo cams relating to two successive cylinders of the corresponding rowof cylinders, whereby reduction in the length of the camshafts and inthe engine cylinder head is effected, wherein the driven gears of twocorresponding camshafts, belonging respectively to the two similar rowsof several cylinders, occupy symmetrical positions with respect to theaxis enabling the cylinder heads of the two rows of cylinders to be madetheoretically to coincide by rotation through around the said axis,whereby it is possible to adopt identical cylinder heads for the twosaid rows of cylinders.

2. lntemal combustion engine according to claim 1, wherein theintermediate shaft is arranged in the longitudinal plane of symmetry ofthe engine, so the two transmission devices relating respectively to thetwo camshalts of the two rows of cylinders are themselves identical.

3. lntemal combustion engine according to claim I, wherein said engineis of the V-form type.

1. In an internal combustion engine comprising at least two similar rowsof several cylinders, an interchangeable overhead camshaft drivearrangement, wherein the camshafts of the two rows of cylinders arerotated, through two chain or notched belt transmission devices andgears, through an intermediate shaft arranged between said rows ofcylinders parallel to the latter and itself rotated by the crankshaft ofthe engine through a generally reducing transmission device, the twosaid transmission devices including respectively two drive gears keyedon the said intermediate shaft at positions selected so that thecorresponding driven gears borne by the camshafts are situated betweentwo cams relating to two successive cylinders of the corresponding rowof cylinders, whereby reduction in the length of the camshafts and inthe engine cylinder head is effected, wherein the driven gears of twocorresponding camshafts, belonging respectively to the two similar rowsof several cylinders, occupy symmetrical positions with respect to theaxis enabling the cylinder heads of the two rows of cylinders to be madetheoretically to coincide by rotation through 180* around the said axis,wHereby it is possible to adopt identical cylinder heads for the twosaid rows of cylinders.
 2. Internal combustion engine according to claim1, wherein the intermediate shaft is arranged in the longitudinal planeof symmetry of the engine, so the two transmission devices relatingrespectively to the two camshafts of the two rows of cylinders arethemselves identical.
 3. Internal combustion engine according to claim1, wherein said engine is of the V-form type.